The objective of this study was to determine the risk for the development of high depressive symptoms in study participants with diagnosed and previously undetected diabetes mellitus compared to those without diabetes in a prospective population-based cohort study in Germany.
We estimated the 5-year cumulative incidence of high depressive symptoms in participants without high depressive symptoms at baseline (n = 3,633, 51.4% men, mean age (SD) 59.1 (7.6) years, 7.0% diagnosed diabetes, 5.3% previously undetected diabetes) from the population-based Heinz Nixdorf Recall study. Diabetes was assessed by self-report, medication, and blood glucose. High depressive symptoms were assessed using CES-D. We calculated odds ratios and their corresponding 95% confidence interval, using multiple logistic regression analyses.
Cumulative 5-year incidences (95% CI) of high depressive symptoms in participants with diagnosed, undetected, and without diabetes were 7.1 (4.2-10.9), 4.1 (1.8-8.0), and 6.5 (5.6-7.4), respectively. The age-sex-adjusted OR for developing high depressive symptoms was 1.22 (0.74-2.03) in participants with diagnosed compared to those without diabetes, and 1.00 (0.59-1.68) after adjustment for BMI, physical activity, education, stroke, and myocardial infarction. The age-sex adjusted OR for developing high depressive symptoms in participants with previously undetected diabetes compared to those without diabetes was 0.72; 0.35-1.48; and fully adjusted 0.62; 0.30-1.30.
We found no significant associations, maybe due to low power. However, our results are in line with a recent meta-analysis suggesting that risk of developing high depressive symptoms in patients with diagnosed diabetes may be moderately higher than in those without diabetes, and that comorbidity may explain in part this association. In participants with previously undetected diabetes, this first longitudinal study indicates that the risk is not increased or may even be decreased. These results support the hypothesis that high depressive symptoms develop due to diabetes-related burden and comorbidity and not due to hyperglycemia or hyperinsulinaemia.